Helical ducting means and method for forming the same

ABSTRACT

Helical ducting is fabricated from edge-precorrugated ribbonstock drawn through a novel die-set to extrude an interlocked seam of a substantially uniform 5-ply thickness with the plys equidistantly overlapping abutting edges of the helical rings of the ducting.

Jan. 7, 1975 United States Patent 11 1 Wood [5 HELICAL DUCTING MEANS AND METHOD 1,492,076 4/1924 Fulton.............,..,...

Lombardi FOR FORMING THE SAME [76] Inventor:

Cecil H. Wood, 60A Industrial Rd., Richmond Hill, Ontario, Canada June 6, 1972 Primary Examiner-C. W. Lanham [22] Filed:

Assistant ExaminerRobert M. Rogers Attorney, Agent, or Firm-C. C. Kent; K. M. Hill 21 Appl. No.: 260,276

edges Of thfi helical rings Of the ducting.

1,042,477 72/49 7 Claims, 14 Drawing Figures Patented Jan. 7,

2 Sheets-Sheet 1 FIG. :2"

HELICAL DUCTING MEANS AND METHOD FOR FORMING THE SAME The present invention is intended to provide (i) a novel method for the manufacture of ducting, and particularly hot-air ducting, and (ii) novel apparatus for the manufacture of such ducting, the same being generally though not necessarily of metal selected from the group consisting of aluminum or alloys thereof, steel and galvanized steel.

BACKGROUND OF THE INVENTION Hotair ducting helically wound from relatively soft alloy ribbon stock wherein the succession of helical rings are interlocked by a continuous seam are known. The seam forming and interlocking is however achieved by a system of spaced roll assemblies around a mandrel so that the seam is roll-formed and interlocked between the rings.

SUMMARY OF THE PRESENT INVENTION A feature of the present invention is, as applied particularly to relatively soft alloy air-conveying ducting, to provide a seam having an inner core and an outer core-wrapping shell, both core and shell being so shaped out of the edge material of soft alloy ribbonstock and related to each other as to provide a continuous joint from which neither the core or the shell can escape laterally or in the plane of the body material of the ducting and at right angles to the seam-axis. This results in the production of flexible ducting having a helically extending seam which is resistant to fluid flow therethrough even after repeated flexing of the ducting.

Another feature of the present invention resides in apparatus for the production of the herein described seam and the interlocking thereof in the fabrication of helically wound ribbon-stock into ducting by the novel step of drawing the seam through a stationary die-set following the arrangement of the adjacent corrugated leading edge of the incoming ribbon-stock and the corrugated trailing edge of the last trailing completed ring 7 of the ducting into lapping and inter-nesting relationship before entering the die-set where the remaining process of forming and interlocking the described seam is performed (except for the flattening of same) after which it is extruded from the die-set. Such apparatus is inexpensive to manufacture, install and service, in contrast to a system of rolls arranged about the perimeter of a mandrel which is costly in the first instance and is considered to require higher maintenance costs.

As preliminary, the process performed by the stated apparatus comprises continuously feeding incoming ribbon stock which is longitudinally corrugated across its entire width at least upon the opposite edges thereof to a forming station and simultaneously feeding to said forming station the trailing corrugated edge of the last trailing completed strip of ducting while rotating said ducting and said ring and also simultaneously placing the leading corrugated edge of said incoming ribbon stock into overlapping and nesting relationship with said corrugated trailing edge of said ring, drawing or pulling the incoming stock and the said trailing edge of the last trailing ring through the die-set and winding the now fully formed seam between a mandrel and a superposed roll for flattening the seam and rotating the in- I coming stock into the form of a new last trailing ring, the last trailing ring being suspended from the mandrel being usually of much greater diameter than the mandrel, the die-set projecting into the nip between the intake side of the mandrel and superposed roll, the upper surface of the die-set being actually curved to the curvature of the roll and fitting snugly into the nip aforesaid as a result.

With the considerations and inventive objects herein set forth in view, and such others as may become apparent from consideration of this disclosure and specification, the present invention consists of and is hereby claimed to reside in the inventive concept which is comprised, embodied, embraced or included in any method, process, construction, composition, arrangement or combination or parts, or new use of any of the foregoing which may herein be exemplified in one or more specific embodiments of such concept, reference being had to the accompanying drawings in which:

FIG. 1 is partially schematic, partially schematic, partially perspective view of a length of flexible ducting in accordance with the invention showing said ducting in its partially manufactured form;

FIG. 2 is a perspective schematic view of an apparatus in accordance with the invention and useful for the manufacture of the inventive flexible ducting as shown in FIG. 1;

FIG. 3 is an enlarged sectional view along the line 3--3 of FIG. 2;

FIG. 4 is an enlarged axial sectional view through the forming station of the apparatus of F IG. 2;

FIGS. 5, 6, 7 and 8 are partial sectional views along the lines 55, 6-6, 7 7 and 88 respectively of FIG. 4 showing therelative dispositions of an exposed longitudinal edge convolution of the already formed flexible ducting and a longitudinal edge convolution of the elongated strip of longitudinally convoluted deformable material entering the forming station of the apparatus;

FIG. 9 is an enlarged, exploded perspective view of the male and female die-members of the novel die-set used for manufacturing flexible ducting;

FIG. 10 is a sectional view through the male and female die members of FIG. 9 taken along the line 10l0 of FIG. 9 and showing the two die members in their operative relative positions;

FIG. 11 is a sectional view similar to that of FIG. 10

but taken along the line 11-11 of FIG. 9;

FIG. 12 is an enlarged cross-section of the seam;

FIG. 13 is an underside plan view of the novel female die-member; I

FIG. 14 is a side elevation of the novel die-set partly fragmented; i

In the drawings, like characters of reference designate similar parts in the several Figures.

COMPLETE DESCRIPTION:

A length of flexible ducting indicated generally at 12 is formed by the helical winding of an elongated strip 13.0f deformable material having longitudinally extending corrugations 14 throughout its entire width. In forming the ducting 12, the strip 13 is wound so that the leading edge corrugation 16 is disposed in overlying relationship with the trailing edge corrugation 18 of the last trailing completed ring 19 of ducting 12 next ahead. These corrugations 16 and 18 are then deformed in a manner which will be explained in greater detail hereinafter to form a helically extending, substantially radially" flattened seam 20.

The sectional structure of seam is best seen by reference to FIG. 8. It comprises a five-layer laminate on each side of its centre line 21 (Fig. 12) of which is a first terminal loop 22 integrally formed with strip material 'on a first axial side of the seam and externally by a second terminal loop 24 integrally formed with the strip material on a second axial side of the centre line, and that the loop 24 substantially completely encircles the loop 22, which loop has already been identified as part of the core 25 of the seam, while loop 24 has been defined as a hook or hook portion.

Flexible ducting formed in this manner has been found to possess an especially useful combination of properties. The novel finding is hereby disclosed that this known seam structure (published in US. Pat. No. 1,796,015 to Francis et a1. 1931 and concerned therein with rigid structures) shows exceptional fluid-tightness even after repeated flexing of the ducting. This makes the ducting particularly useful for high pressure air handling and industrial exhaust systems.

The apparatus indicated generally at 26 includes a forming station generally designated 28. The elongated strip 13 of deformable material having longitudinally extending corrugations 14 throughout its width is fed continuously from a set of rolls in the direction of arrow A to the forming station 28 at which it is secured to the exposed longitudinal trailing edgecorrugation 18 of the last formed, last trailing ring 29 which, as ducting 12 continuously feeds away from the forming station 28 in the direction of the arrow B.

A generally upright frame indicated generally 30 is supported on a floor 31 and has mounted thereon a pair of upper and lower, corrugated squeeze rolls 32 and 34 disposed in tangential abutment with each other. The

rolls 32 and 34 are mounted on the frame 30 for rotation in opposite directions as indicated by the arrows C and D. In the particular embodiment illustrated, the upper roll 32 is mounted for free rotation about its longitudinal axis in the direction of the arrow C while the lower cylindrical member 34 is mounted so as to be driven for rotation in the direction of the arrow D by any suitable drive means. The rolls 32 and 34 have smaller diameters than the ducting 12 so that the lower roll 34 can be disposed completely within the ducting In their abutting outer peripheral surfaces, the upper and lower rolls 32 and 34 respectively are provided with cooperating, helically extending, peripheral corrugations between which the corrugated strip 13 and the left-hand end of the ducting 12 are received in edgeoverlapping disposition. It will be noted that the lower roll 34 is peripherally corrugated to provide alternating radially extending, generally sinusoidal crests 36 and troughs 38. Similarly, the upper roll 32 is peripherally corrugated to provide alternating, radially extending,

. generally sinusoidal crests 40 and troughs 42, the crests 36 being received within the troughs 42 and the crests 40 being received within the troughs 38.

In proximity to the right-hand ends of the rolls 32 and 34, these members are provided with peripheral surfaces which are modified in a manner now to be described and for a purpose which will become apparent as the description herein proceeds. In particular, the lower roll 34 is provided with a surrounding flattened trough 44. The upper cylindrical member 32 surrounding flattened zone 54 bounded by a pair of troughs 56 and 58 and connected to zone 54 via side-walls 60 and 62. In the assembled form, the zone 54 defines with the trough 44 a circumscribing narrow chamber 46 axially bounded by the walls 60 and 62, the troughs 44 being disposed in opposition to the axially outer portion 48 and of the flattened trough 44.

The die and spike set collectively designated 26 is comprised of a female die member 64 and an associated male die member (the spike) 66, which are each supported on frame 30 by arms 68. Member 66 comprises a generally upstanding section 70 by means of which it is secured to its supporting arms 68. At its upper end, the member 66 curves inwardly as at 71 to form a die spike or tapered distal end 72. The lower surface configuration of the spike 72 progressively flattens from is outer end (FIG. 10) towards its inner end 74 (FIG. 11).

The female die member 64 is provided with a supporting section 74 by means of which it is mounted on its associated arms 68. At its inner end, the female die member 64 has an upper, generally horizontal web 76 integrally formed through side-walls 78 with a pair of opposed inwardly' projecting flanges 80. The web 76, walls 78 and flanges 80 define a drawing cavity 82 into which spike 72 extends. The transverse dimensions of the cavity 82 as well as the transverse separation between the lips 80 progressively decrease towards the extruding end of the die member 64.

In operation, assuming that the forming operation is in progress, the already formed ducting 12 is supported by the lower cylindrical member 34 and is disposed between the matting peripheral corrugations of the upper and lower rolls 32 and 34 respectively. As the lower member 34 is driven in the direction of the arrow D, ducting 12 will be rotatably generated in the direction of the arrow E (FIGS. 2 and 4) and, since the peripheral convolutions of the rolls 32 and 34 are helically disposed, ducting 12 will be axially advanced in the direction of the arrow B (FIG. 2). As the strip l3 is consequently moved in the direction of the arrow A, its

edge corrugation or crest 16 is received within thecated in FIG. 6.

As the rotation of the ducting 12 continues in the direction of the arrow E, the overlying edge corrugations 16 and 18 of the ducting l2 and the strip 13 respectively are gradually and jointly deformed by engagement between the inner surface of the die chamber 82 and the outer surface of the spike 72 to form a two ply, generally axially orientated, flattened crest 84 axially bounded by generally radially orientated, doublethickness side-walls 86 and 88 (FIG. 7). As the evolving seam moves towards the inner end of the die chamber 82, the engagement of the side-walls 86 and 88 with the converging flanges of the female die member 64 causes these side-walls 86 and 88 to be deformed in generally axial directions towards each other to form said first and second terminal loops 22 and 24 respectively (FIG. 8) which together provide a positive coupling between each spiralring of ducting. The associated loops 22 and 24 gradually move into the nip between the upper and lower rolls 32 and 34 respectively so as to be disposed in the chamber 46, in which chamber these loops are radially compressed to form the helically extending seam 20, the associated flattened crests 56 and 58 and the sections 48 and 50 of the flattened zone 44 having disposed therebetween the axially adjacent portions of the ducting l2 and the strip 13.

The complete seam as such comprises hooks or loops 22 and 24 (otherwise the leading and trailing edge corrugtions l8 and 16 respectively), the said core 25 and the horizontally opposed grooves 90 and 92 orientated toward the seam centreline 21 the former of which receives hook 24 while the latter function as a two-ply roll to provide laterally balanced equally compressible five-ply thickness to the seam as-a-whole. It also in cludes, encircling and enclosing core 25 what was origi nally the corrugated trailing edge 16 but not constitutes an enclosing shell collectively designated (including hook 24) 94, and the just noted roll 92 which includes inmost ply 96, while the groove 90 includes inmost ply 98 by which two plys the seam is united to adjacent rings of the ducting.

CLAIMCONSONANT CONCLUDING DESCRIPTION To conclude this disclosure in terms and expressions generally consonant with those by which the present invention is defined and claimed, such invention comprises the process of windably fabricating out of relatively soft alloy ribbon stock which has been precorrugated as at 14 longitudinally at least along the opposite elongated edges 17 and 17 into helical duct 12 out of rings generated by the rotation of said stock and by interlocking while so rotating, the adjacent leading and trailing edges 23 and 23 respectively of successive co-axial said rings as viewed relative to the axial direction 26 of said duct-generation by means ofa continuous seam 20, comprising the step of exerting a longitudinal tensile effort upon said stock as indicated by arrows A and E (Figs. 3 and 4) and upon the trailing corrugated edge of the last trailing ring 29 while said leading and trailing edges thereof 17' and 23" respectively are passing in a substantially straight-line direction through a stationary seam-forming die-set generally designated 33, (i) said leading edge lapping said trailing edge, (ii) the axis of the die-set being generally tangent to the last trailing ring, (iii) said tensile effort being applied to said stock and ring trailing edge closely adjacent said extruding end, (iv) said ring and duct being axially rotated about a fixed horizontal axis designated by said arrow 36.

The product of the process just stated consists of duct or ducting l2 helically wound into a continuous succes sion of rings 15 interlocked between adjacent edges by a continuous helical seam which, at right angles to its length is seen to comprise a flattened core 22 and a flattened shell 24 surrounding said core, said core embodying a mid-panel 22, and a pair of lateral panels 39 and 41 parallel with, and underlying said mid-panel being integral therewith and a stem 43 centrally disposed with respect to said seam connecting said core in wherein successive rings forming said ducting are interlocked by the seam which has now been described, apparatus is employed which essentially comprises in combination a tensile effort-applying assembly embodying with a source of power, a stationary cylindrical axially rotatable mandrel 34 and a stationary squeeze roll 32 axially parallel and in operative rotatable contact with said mandrel, a stationary female diemember 64 closely adjacent said mandrel and roll, said die-member including a shoe 67 adapted to receive in overlapping relationship .two adjacent corrugated edges 16 and 18 of ribbon-stock in nested relationship, (Figs. 5-8) one edge being the trailing edge 23 of the last trailing ring 29 and the other the leading edge 17' of the as-yet unwound stock and to seam-form said edges upon the application of said tensile effort upon said stock and the last trailing one of said rings by said effort applying assembly, said shoe including seam-forming means 69, a heel 71 which projects into the nip 73 between said mandrel and said roll in the form of the aforesaid seam-shape extruding end 37.

The apparatus also includes, for the production of a better seam a male core-forming die-member generally designated 66 essentially in the form of a curved spike projecting into the aforesaid sole towards said toe. The male die-member curves downwardly from the distal end 74 ofthe spike and widens into the vertical connecting portion 70, the male die-member being positioned below the female die-member.

The shoe 67 has upon the sole thereof an elongated open-ended drawing cavity 73 which is wider and deeper at the heel of the shoe than at the toe, the cavity having side walls 78 surmounted by flanges 80 which project inwardly toward each other over cavity 73 increasingly from heel to toe so as to define an elongated opening 73 which grows progressively narrower towards the toe.

Various modifications may be constructed or performed within the scope of the inventive concept disclosed. Therefore what has been set forth is intended to illustrate such concept and is not for the purpose of limiting protection to any herein particularly described embodiment thereof.

I claim:

1. The process of fabricating duct by winding soft alloy ribbon stock into helical rings which have been pre-corrugated longitudinally at least along the opposite elongated edges thereof said rings being generated by the rotation of said stock and by interlocking while so rotating, the adjacent leading and trailing edges of successive co-axial said rings as viewed relative to the axial direction of ductfabrication by means of a continuous seam, which process comprises the step of exerting a longitudinal tensile effort upon said stock and upon the trailing corrugated edge only of the last complete trailing ring while said leading and trailing edges thereof respectively are passing in a substantially straight-line direction through a stationary seamforming die-set,

i. said leading edge lapping said trailing edge,

ii. the axis of said die-set being generally tangent to said last trailing ring,

iii. said tensile effort being applied a. to said stock and b. to said last complete ring; trailing edge only closely adjacent the output end of said die-set.

2. For use in the fabrication of ducting formed of relatively soft alloy ribbon-stock helically wound into a continuous helical seam which, in cross-section at right anles to its length is seen to comprise a flattened core and a flattened shell surrounding said core and overlying a centrally disposed neck integral with one edge into which neck projects a centrally disposed stern integral with another adjacent edge, the invention which takes the form of fabricating means comprising in combination a tensile effort-applying assembly embodying with a source of power a stationary cylindrical axially rotatable mandrel and a stationary squeeze-roll axially parallel and in operative rotatable contact with said mandrel, a single stationary female seam-forming die member closely adjacent said mandrel and roll, said die-member including a shoe, said shoe being adapted 0,

a. receive in overlapping relationship two adjacent edges of ribbon stock in corrugated nested relationship, one edge being the trailing edge of the last complete trailing ring and the other the leading edge of as-yet-unwound stock and b. seam-form said edges upon the application of said tensile effort upon said as-yet-unwound stock and trailing edge of the last trailing complete ring by said effort applying assembly, said shoe having i. seam-forming means,

ii. a heel into which said stock and ring is admitted in un-seamed form and iii. a toe which projects into the nip between said mandrel and roll in the form of a seam extruding end,

. 3. The invention according to claim 2, in which said spike projects into said shoe towards said toe, curving downwardly from the distal end thereof to widen into a vertical connecting portion positioned below said female die-member.

4. The invention according to claim 3 in which said shoe has an elongated drawing cavity which is wider and deeper at the heel of said shoe than at the toe, said cavity having side walls edged by flanges which project inwardly toward each other increasingly from said heel to said toe so as to define an elongated opening between said flanges which grows progressively narrower towards said toe, said core-forming die-member curving downwardly from the distal end of said spike and widening into a vertical connecting portion said coreforming die-member being positioned below said female die-member, said core-forming portion entering said cavity generally at the entering heel-end of said elongated opening 5. The invention according to claim 2 in which said shoe has an elongated open-ended drawing cavity which is wider and deeper at the heel of said shoe than at the toe, said cavity having side walls edged by flanges which project inwardly toward each other over said cavity increasingly from said heel to said toe so as to define an elongated opening which grows progressively narrower towards said toe.

6. The invention according to claim 5 in which dieset and includes a male core-forming'die-member said core-forming die-member being said shoe the crosssection of said spike conforms generally to that of the interior of said cavity.

7. The invention according to claim 4, in which said female die-member: 1

a. includes a horizontal connecting portion,

b. extends below said core-portion and c. is disposed generally in the horizontal.

l l l 

1. The process of fabricating duct by winding soft alloy ribbon stock into helical rings which have been pre-corrugated longitudinally at least along the opposite elongated edges thereof said rings being generated by the rotation of said stock and by interlocking while so rotating, the adjacent leading and trailing edges of successive co-axial said rings as viewed relative to the axial direction of duct- fabrication by means of a continuous seam, which process comprises the step of exerting a longitudinal tensile effort upon said stock and upon the trailing corrugated edge only of the last complete trailing ring while said leading and trailing edges thereof respectively are passing in a substantially straight-line direction through a stationary seam-forming die-set, i. said leading edge lapping said trailing edge, ii. the axis of said die-set being generally tangent to said last trailing ring, iii. said tensile effort being applied a. to said stock and b. to said last complete ring trailing edge only closely adjacent the output end of said die-set.
 2. For use in the fabrication of ducting formed of relatively soft alloy ribbon-stock helically wound into a continuous helical seam which, in cross-section at right anles to its length is seen to comprise a flattened core and a flattened shell surrounding said core and overlying a centrally disposed neck integral with one edge into which neck projects a centrally disposed stem integral with another adjacent edge, the invention which takes the form of fabricating means comprising in combination a tensile effort-applying assembly embodying with a source of power a stationary cylindrical axially rotatable mandrel and a stationary squeeze-roll axially parallel and in operative rotatable contact with said mandrel, a single stationary female seam-forming die-member closely adjacent said mandrel and roll, said die-member including a shoe, said shoe being adapted to, a. receive in overlapping relationship two adjacent edges of ribbon stock in corrugated nested relationship, one edge being the trailing edge of the last complete trailing ring and the other the leading edge of as-yet-unwound stock and b. seam-form said edges upon the application of said tensile effort upon said as-yet-unwound stock and trailing edge of the last trailing complete ring by said effort applying assembly, said shoe having i. seam-forming means, ii. a heel into which said stock and ring is admitted in un-seamed form and iii. a toe which projects into the nip between said mandrel and roll in the form of a seam extruding end, and a male core-forming die-member essentially in the general form of a spike projecting into said shoe towards said toe.
 3. The invention according to claim 2, in which said spike projects into said shoe towards said toe, curving downwardly from the distal end thereof to widen into a vertical connecting portion positioned below said female die-member.
 4. The invention according to claim 3 in which said shoe has an elongated drawing cavity which is wider and deeper at the heel of said shoe than at the toe, said cavity having side walls edged by flanges which project inwardly toward each other increasingly from said heel to said toe so as to define an elongated opening between said flanges which grows progressively narrower towards said toe, said core-forming die-member curving downwardly from the distal end of said spike and widening into a vertical connecting portion said core-forming die-member being positioned below said female die-member, said core-forming portion entering said cavity generally at the entering heel-end of said elongated opening.
 5. The invention according to claim 2 in which said shoe has an elongated open-ended drawing cavity which is wider and deeper at the heel of said shoe than at the toe, said cavity having side walls edged by flanges which project inwardly toward each other over said cavity increasingly from said heel to said toe so as to define an elongated opening which grows progressively narrower towards said toe.
 6. The invention according to claim 5 in which die-set and includes a male core-forming die-member said core-forming die-member being said shoe the cross-section of said spike conforms generally to that of the interior of said cavity.
 7. The invention according to claim 4, in which said female die-member: a. includes a horizontal connecting portion, b. extends below said core-portion and c. is disposed generally in the horizontal. 